A considerable amount of freight, particularly automobile parts and related items, have always been required in automobile manufacturing areas, of which Michigan is but one example. While many of these areas require a large amount of items delivered to them, to an important degree, the freight from such areas consists mainly of automobiles. Unfortunately, the commercial transport of automobiles moved by truck presently requires specialized vehicles specifically designed for automobile transport, since automobiles cannot normally be accomodated by standard semitrailer trucks, particularly in efficient quantities.
U.S. Pat. No. 2,432,228, for instance, shows a tandem trailer specially designed to carry automobiles. In the trailers taught by the patent, the automobiles are loaded onto a top platform, with additional automobiles being loaded on a deck beneath them. The top platform poses a serious impediment to hauling general freight, however, greatly reducing the versatility of the truck.
The back-haul problem is, therefore, actually compounded by the use of specialized trucks in that they themselves must return empty, once they have delivered a load of automobiles to its destination.
Much thought has been devoted to solving the back-haul problem, and in the case of truck deliveries to automobile manufacturing areas, for example, there have been attempts to design trucks that can accommodate both automobiles, as well as general freight.
U.S. Pat. No. 3,043,454, is an example of an attempt to construct a semitrailer truck that is capable of carrying automobiles, as well as general freight. To accomplish this, the patent teaches the use of an elevating mechanism which raises the automobiles initially placed in the truck to an overhead position. Following overhead loading, additional automobiles may be placed under those suspended by the elevating mechanism. Presumably, when the truck is to be used for carrying general freight, the elevating mechanism is raised out of the way, to a location near the top of the truck.
While the mechanism of the invention is ingenious, it is also complex, and greater cost and complexity. In addition, the loading and unloading producedures attendant to storing automobiles in the upper part of the truck would demand considerable skill for their successful accomplishment, presenting significant opportunities for mistakes and the possibility of serious consequences, both in terms of physical injury and property damage in the event of mischance.
The problem of designing a truck capable of handling both general freight and automobiles has also been greatly compounded by the fact that federal and state highway regulations impose strict limitations on the external dimension of semitrailer trucks operating over the nation's highways. At the same time, there has been increasing competition between the available forms of freight transportation, rail, air, and truck, forcing ever increasing efforts to improve efficiencies and lower ton-mile costs. This has led to such expedients as low profile tires to increase the volume of the cargo space within the practical dimensions, reductions in the clearance distance between truck bed and road, and similar expedients.
While such design adjustments have helped considerably, they are limited by the very nature of semitrailer trucks. The top of the front end of a semitrailer, for example, is restricted as to available height by the regulations referred to, while the bottom of the front end must be high enough so that it will fit over the coupler of the tractor truck used to pull the semitrailer. The limited space available between the height of the top and the bottom of an ordinary semitrailer unfortunately in the case of most standard sized automobiles makes it impossible to position one automobile over another in the front of the semitrailer, as must be done if an automobile load is to be maximized.
Now, however, a method has been found by which a semitrailer can be constructed to permit the efficient transportation of automobiles.
The inventive design allows as many as six standard sized automobiles to be carried in a semitrailer, and yet permits the dimensions of the truck to comply with the limitations specified in the state and federal regulations referred to.
The semitrailer of the invention can with a minimum of effort, readily be converted from its automobile hauling mode to its general freight hauling mode, making it much more versatile and considerably alleviating the back-haul problem in automobile manufacturing areas.
The semitrailer of the invention can be relatively inexpensivly constructed, without any need for complex apparatus. Furthermore, the type of semitrailer contemplated by the invention is simple in design, and consequently assures increased reliability, lower maintainence, and longer life.